Protonic EDLC cell based on chitosan (CS): methylcellulose (MC) solid polymer blend electrolytes

Abstract

In this work, preparation and application of solid polymer blend electrolytes (SPBEs) based on chitosan: methylcellulose (CS:MC) incorporated with various amounts of ammonium iodide (NH4I) salt are described. Solution cast technique was adapted for the preparation of the SPBE films. Structural investigation and extent of interaction of the NH4I salt with the CS:MC film surface were conducted through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements. Electrical DC conductivity of the prepared samples was studied by electrochemical impedance spectroscopy. It is confirmed through transference number (TNM) analysis that ions are the dominant charge carrier in the polymer electrolyte system, in which the ionic (tion) and electron (tel) transference numbers were found to be 0.934 and 0.036, respectively. Through the use of linear sweep voltammetry (LSV), the CS:MC:NH4I system is found to experience electrolyte degradation at 2.1 V. The polymer blend electrolyte sample with highest DC conductivity property was also used as separator in electrical double-layer capacitor (EDLC) cell. Two identical activated carbon electrodes were used to sandwich the electrolyte film. Cyclic voltammetry (CV) was used to show the capacitive behavior of the fabricated EDLC cell, in which no redox peaks were observed. The EDLC was examined for 100 cycles at current density of 0.2 mA/cm2. The values of specific capacitance and equivalent series resistance were determined to be 1.76 F/g, and 650 to 1050 Ω, respectively.